42 J. SMITH ON THE GENERA OF FERNS. 



the apices of the venules of the proximate fascicle, in an an- 

 gular or arcuate manner, and produce, on their points of 

 meeting, or exterior side, one or more outwardly directed, 

 (excurrent) tertiary veins (veinleis), which are either free and 

 terminate in the areoles or margin {^g. 7. 9. 10. o. H. a.) or 

 anastomose in the angular junction of the next superior pair 

 of venules {^g. 10. 6. 11. &.); or, the whole venation is near- 

 ly uniform and combined, forming equal or unequal-sided 

 areoles, with all the venules connected (reticulated) {fig' 12, 

 13, 14.); or irregularly combined, and the areoles producing, 

 from their sides, cxcurrent or recurrent, simple, forked, or 

 brachiate, straight or uncinate, free or conniving veinlets, 

 which terminate in the unequal sided areoles {compound anas- 

 tomosing') (fig. 15). The whole being more or less superfi- 

 cial, and distinct, plane, or elevated {external), or immersed 

 in the substance of the frond, and then often indistinct (in- 

 te?-nal). 



The sporangiferous receptacle is a thickened point or length- 

 ened portion of the ultimate venules or veinlets, and is either 

 formed on their apex {terminal), or between their apex and 

 base {medial), or on the point of forking {axillary), or on the 

 angular crossings or points of confluence of two or many ve- 

 nules or veinlets {compital), or the whole or a portion of the 

 disc of the frond is changed in texture, and closely occupied 

 by the sporangia {amorphous). It is generally superficial, 

 sometimes immersed in the substance of the frond, or consid- 

 erably elevated, and then globose or columnar. 



The sporangia are transparent, globose, oval, or pyriform, 

 unilocular cases, each girded by a more or less complete, 

 elastic articulated ring, or destitute of a ring, then sometimes 

 oblong, opaque and multilocular ; usually pedicellate, rarely 

 sessile, produced in crowded masses {sori) on each receptacle; 

 rarely solitary or few, sometimes pilose, and a nmnber often 

 abortive and deformed. 



The sori are collections of sporangia, and have the same 

 form, position, and direction, as the receptacles; therefore 

 round, elongated, or amorphous, and seated on or close to the 



